1. Field of Invention
The present invention relates to devices for sharpening chainsaws and more particularly to an adjustable chainsaw file guide and holder.
2. Description of Prior Art
It is common practice in the industry to use a round file to sharpen the cutting teeth of a chainsaw. Such files typically range in size from 1/8 to 1/4 inches in diameter and 6 to 8 inches in length and are held in a holder such as the chainsaw file holder disclosed in U.S. Pat. No. 3,867,853 to John Lawless. Such file holders facilitate the holding and guiding of the file during the sharpening operation.
One disadvantage with the Lawless device and other presently used file holders is that the space between file clamping points is fixed and hence separate holders of different lengths must be used to clamp the ends of different length files. It is also advantageous to be able to successively clamp different sections of a chainsaw file or to shorten up clamping point spacing to prevent file bending. Being non-adjustable, Lawless and other existing file holders do not have this capability.
The present invention overcomes the above-described disadvantages by providing an adjustable file guide and holder which is capable of having its file clamping points adjusted relative to each other to anywhere along the length of the file being held. This adjustability feature eliminates the need for separate holders for different length files and also allows different portions of the file to be successively used.
Another disadvantage of the Lawless file holder is that the thumb screw 25 which secures or clamps the tang end of the file tends to cock the file to one side of the vertex of the guide surfaces as the flat end of the thumb screw is rotated tightly against the file. The present invention overcomes this problem by providing a locking mechanism which will not cock the file to one side or the other, but will instead positively center the file beneath the aforementioned guide surface vertex.
The present invention also provides a degree of safety and economy not found in the prior art. Heretofore, file guide holders have consisted of a single machined body portion having set screws. In these prior art devices, the tang end of the file with its file handle extends beyond one end of the holder. If the handle of the file were to break off under downward pressure during the filing operation, as has been known to occur, a hand injury such as a puncture wound almost certainly would follow. To protect against this possibility the present invention provides a special handle portion formed on the frame of the holder. Also, since the integral body is formed of a stamped part, the more costly machined frames of prior art devices have been eliminated.